package com.hc.programming.array;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * 40.给定一个候选人编号的集合 candidates 和一个目标数 target ，找出 candidates 中所有可以使数字和为 target 的组合。
 * candidates 中的每个数字在每个组合中只能使用 一次 。
 * 注意：解集不能包含重复的组合。
 * <p>
 * 示例 1:
 * 输入: candidates = [10,1,2,7,6,1,5], target = 8,
 * 输出:
 * [
 * [1,1,6],
 * [1,2,5],
 * [1,7],
 * [2,6]
 * ]
 * <p>
 * 示例 2:
 * 输入: candidates = [2,5,2,1,2], target = 5,
 * 输出:
 * [
 * [1,2,2],
 * [5]
 * ]
 * <p>
 * 提示:
 * 1 <= candidates.length <= 100
 * 1 <= candidates[i] <= 50
 * 1 <= target <= 30
 *
 * @author huangchao E-mail:fengquan8866@163.com
 * @version 创建时间：2024/6/14 21:46
 */
public class 组合总和II {
    public static void main(String[] args) {
        System.out.println(combinationSum2(new int[]{10, 1, 2, 7, 6, 1, 5}, 8));
        System.out.println(combinationSum2(new int[]{2, 5, 2, 1, 2}, 5));
    }

    public static List<List<Integer>> combinationSum2(int[] candidates, int target) {
        Arrays.sort(candidates);
        List<List<Integer>> res = new ArrayList<>();
        calc(candidates, target, 0, 0, 0, new int[target / candidates[0] + 1], res);
        return res;
    }

    private static void calc(int[] candidates, int target, int start, int level, int sum, int[] arr, List<List<Integer>> res) {
        for (int i = start; i < candidates.length; i++) {
            if (candidates[i] > target) break;
            if (i > start && candidates[i] == candidates[i - 1]) continue;
            arr[level] = candidates[i];
            int newSum = sum + candidates[i];
            if (newSum > target) break;
            if (newSum == target) {
                arr2List(arr, level, res);
            } else if (newSum < target && i < candidates.length - 1) {
                calc(candidates, target, i + 1, level + 1, newSum, arr, res);
            }
        }
    }

    private static void arr2List(int[] arr, int level, List<List<Integer>> res) {
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i <= level; i++) {
            list.add(arr[i]);
        }
        res.add(list);
    }
}
